TNF and obesity due to melanocortin 4 receptor deficiency: We hypothesize that additional obesity-related metabolic factors may also play a similar or even synergistic pro-inflammatory role in the placenta as in vitro studies have demonstrated that treatment of human choriocarcinoma BeWo trophoblast cells with palmitic acid, which is the most abundant circulating free fatty acid in obesity, in combination with TNF-α led to feed-forward production of both TNF-α along with increases in IL-6 [68].